In present day medical sciences, there is a distinct trend toward the unit-dose systems wherein a pre-determined quantity of drugs can be pre-packaged and stored for extended periods of time and usable on quick notice for emergency situations which may arise in the clinic or the operating room. Heretofore, conventional syringes have been utilized to aspirate the medicament from a closed vial by puncturing a diaphragm across the vial with the cannula, aspirating the syringe, and thereby filling the syringe for usage. This procedure is quite time consuming and, additionally, has the disadvantage of drugs being aspirated from a vial and the drug replaced by water or a similar liquid substance.
Several unit-dose devices have been available on the market but have had several distinct disadvantages. One such device requires an expensive holder to which a sterilized cannula must be attached and, due to the expense of the holder, is often not readily available at the time of need, the expense precluding the availability of additional holders. Additionally, such devices do not have means for pre-assembly in a non-activated condition and their more common activation movement requires at least a turn of some rotational degree and, more commonly, a combination of insertion, seal break-off, and a twisting motion which is relatively complex to the uninitiated user. Additionally, none of the existing devices provides aseptic protection over all drug container and drug contact surfaces to the moment of infusion. At best, such devices provide minimal drug contact surfaces which, up to the moment of aspiration for a show of blood when a venipuncture is necessary, are not exposed to the drug, but which immediately upon aspiration pull their plunger or plug back across vial surfaces which have been exposed to the air and which consequently can subject the infused drugs to aerobic contamination.
Probably one of the most important deficiencies of such existing prior art is that none of these devices provides a visual observation of aspirated blood without introducing the blood to the drug container.
Lastly, because of the typically rotational activation nature of such existing syringe devices, these devices are necessarily round pg,3 tubular members or generally cylindrical in shape, thereby requiring cylindrical embodiments in co-acting holder, activators and similarly related components of such devices.
Prior art devices having the limitations enumerated above can be found in the United States Pats. issued to R. W. Ogle, such as Nos. 3,303,846; 3,330,280; 3,376,866; 3,378,008; and the patent to Fred M. Killinger, no. 3,841,329.